1. Field of the Invention
The present invention pertains to medical equipment, and more particularly, to a therapeutic ultrasound system for ablating obstructions within tubular anatomical structures such as blood vessels.
2. Description of the Prior Art
A number of ultrasound systems and devices have heretofore been proposed for use in ablating or removing obstructive material from blood vessels. However, all of these systems and devices generally encounter some problems which are not always adequately addressed by these systems and devices.
A first type of problem relates generally to the effective transmission of ultrasound energy from an ultrasound source to the distal tip of the device where the ultrasound energy is applied to ablate or remove obstructive material. Since the ultrasound source, such as a transducer, is usually located outside the human body, it is necessary to deliver the ultrasound energy over a long distance, such as about 150 cm, along an ultrasound transmission wire from the source to the distal tip. Attenuation of the acoustical energy along the length of the transmission wire means that the energy reaching the distal tip is reduced. To ensure that sufficient energy reaches the distal tip, a greater amount of energy must be delivered along the transmission wire from the source to the distal tip. This transmission of increased energy along the transmission wire may increase the fatigue experienced by the transmission wire at certain critical locations, such as at the connection between the transducer and the transmission wire.
In addition to the above, it is important to be able to conveniently connect and disconnect the ultrasound transmission member from the transducer without creating unnecessary stresses on the ultrasound transmission wire, or weakening the ultrasound transmission wire. Since the transducer is a non-sterile unit, and the ultrasound transmission wire is a sterile unit, a transducer can be used with numerous different ultrasound transmission wires in numerous different procedures. Therefore, there is also a need to provide a removable connection between the ultrasound transmission wire and the transducer that can effectively transmit ultrasound energy while maintaining the integrity of the ultrasound transmission wire.
A second type of problem relates to the need for accurately positioning the ultrasound device inside a patient's vasculature, and in particular, where the vasculature contains smaller and more tortuous vessels. To address this need, flexible and low-profile ultrasound devices have been provided which allow the device to be navigated through small and tortuous vessels. However, these devices have not been completely satisfactory in meeting these navigational needs.
A third type of problem relates to the removal of particles that are produced when the obstructive material is ablated or broken up. It is important that these particles be removed from the patient's vascular system to avoid distal embolization and other clinical complications.
Thus, there still exists a need for improved ultrasound systems having ultrasound devices or catheters which address the aforementioned problems.